Wireless system for determining displacement of spinning components

ABSTRACT

A wireless system for determining the displacement of spinning components of a differential assembly, including a differential case having a hollow interior space; a differential assembly having an actuator including an electromagnet having a coil, a spinning component selectively engaged with a differential gear arrangement and at least one sensor assembly non-rotatably mounted to the differential case including at least one sensor communicatively coupled to a printed circuit board, a transmitter and a power source. The sensor assembly extends axially and radially within the differential case and at least one sensor is-configured to directly sense the axial displacement of the spinning component and the sensor assembly is configured generate a signal representing the axial displacement of the spinning component into a signal that is wirelessly transmitted to a receiver positioned outside the differential case.

RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication Nos. 62/202,233 filed on Aug. 7, 2015 and 62/311,087 filedon Mar. 21, 2016, the entire disclosures of which are herebyincorporated by reference.

FIELD

The present disclosure relates to a wireless system for determining thedisplacement of spinning components, and more particularly, a wirelesssystem for determining the displacement of gears in a lockingdifferential.

BACKGROUND

Motor vehicles include multiple systems where it is beneficial to sensethe position or state of a spinning or rotating components. For example,spinning components are used in locking differentials, axle disconnectsystems and power take off units. Sensing the position or state ofspinning components can be difficult. In locking differentialsspecifically, spinning gears can be moved in and out of engagement withother gears. The distance between the gears can be indirectly measuredwhen the gears are engaged by measuring the effects of the engagement.However, in some arrangements, the conditions required to indirectlymeasure the effects of engagement may not always be met. Thus, the onlydefinitive way to determine if the gears have engaged is to measure thedistance traveled by the moving/spinning gear.

A current method for sensing the position of spinning components usessensors mounted rigidly around the spinning component, and the sensorstranslate the movement of the spinning component tom-non-spinningcomponent. The translation from spinning to non-spinning introducessignificant error and cost. For example, any run-out of the spinningcomponent will appear to be small axial movements and, thus, added noiseto the measured signal increasing error. These translating sensingsystems also have several additional components, each that can addadditional noise and cost to the system. Additionally, there is contactbetween a spinning component and a non-spinning components creatingadditional wear that decreases the life of the system and increases thecost of the system.

A potential solution is to embed the sensor with the spinningcomponents, allowing the sensor to spin along with the components;however, difficulties arise in getting power to the sensor andtransmitting the signal out of the sensor. Wired sensor systems do notwork because the wires will quickly wrap around the spinning components.

Therefore, it would be desirable to have a wireless system that directlysenses the displacement of the spinning component.

SUMMARY

A wireless system for determining the displacement of spinningcomponents of a differential assembly includes a differential casehaving a hollow interior space, a differential assembly having anactuator including an electromagnet having a coil, a spinning componentselectively engaged with a differential gear arrangement and at leastone sensor assembly non-rotatably mounted to the differential caseincluding at least one sensor communicatively coupled to a printedcircuit board, a transmitter and a power source. The differential casehouses the differential gear arrangement. A portion of the sensorassembly extends axially and radially within the differential case andat least one sensor is located in the hollow interior space of thedifferential case and axially adjacent to the spinning component of thedifferential assembly. At least one sensor is configured to directlysense the axial displacement of the spinning component. The sensorassembly is configured to generate a signal representing the axialdisplacement of the spinning component. The transmitter is capable ofwirelessly transmitting the signal to a receiver positioned outside thedifferential case.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as other advantages of the present embodiments willbecome readily apparent to those skilled in the art from the followingdetailed description when considered in the light of the accompanyingdrawings in which:

FIG. 1 is a cross-sectional view of a preferred embodiment of thewireless system in a locking differential;

FIG. 2 is a cross-sectional view of another preferred embodiment of thewireless system in a locking differential in a disengaged state;

FIG. 3 is a cross-sectional view of the wireless system of FIG. 2 in alocking differential in an engaged state;

FIG. 4 is a cross-sectional view of another preferred embodiment of thewireless system in a locking differential;

FIG. 5 is a perspective of another preferred embodiment of the wirelesssystem in a locking differential;

FIG. 6 is a detailed view of the energy generations system of thewireless system of FIG. 5; and

FIGS. 7a-b are schematic views of a shaker-type energy generationsystem.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is to be understood that the embodiments may assume variousalternative orientations and step sequences except where expresslyspecified to the contrary. It is also to be understood that the specificdevices and processes illustrated in the attached drawings, anddescribed in the following specification, are simply exemplaryembodiments of the inventive concepts defined in the appended claims.Hence, specific dimensions, directions or other physical characteristicsrelating to the embodiments.

Turning now to FIG. 1, one embodiment of a wireless system 10 forspinning components is depicted. The sensing system 10 is depicted in alocking differential assembly 12 to determine the axial position of thelocking gear within a vehicle's locking differential assembly 12;however, the sensing system 10 may also be used in other systemsincluding, but not limited to, power-take-off units, axle disconnectsystems, etc.

As shown in FIG. 1, the differential assembly 12 includes a differentialcase 14. The differential case 14 is located in a differential housing(not shown) and is mounted for rotation in the differential housing. Thedifferential case 14 includes a hollow interior space 14 a.

A differential spider shaft 16 is located within the differential case14. The spider shaft 16 extends across the hollow interior space 14 a ofthe differential case 14. In one embodiment, an end portion 16 a of thespider shaft 16 is secured within an aperture 14 b of the differentialcase 14.

The differential assembly 12 includes a differential gear arrangementhaving a first differential side gear 18, a second differential sidegear (not shown), a first differential pinion gear 24 and a seconddifferential pinion gear (not shown). The first differential side gear18 is mounted on the end portion 16 a of the spider shaft 16 within thedifferential case 14. The differential case 14 houses the differentialgear arrangement. As shown in FIG. 1, the spider shaft 16 can extendthrough an aperture 18 a in the first differential side gear 18.

The first differential side gear 18 has a set of teeth 20circumferentially there around. The differential side gear teeth 20 arein selective meshed engagement with a set of teeth 22 on the firstdifferential pinion gear 24. The differential side gear teeth 20 arealso meshed with teeth on the second differential pinion gear (notshown). The differential side gear teeth 20 are on a first side 18 a ofthe first differential side gear 18. The first side 18 a faces inwardlyinto the differential case 14.

The first differential side gear 18 has a second side 18 b opposite thefirst side 18 a. The second side faces outwardly. The second side 18 bof the first differential side gear 18 has an axially extending pocket18 c extending into the first differential side gear 18. The pocket 18 creceives a first end-portion 26 a of a biasing member 26 therein. Thebiasing member 26 may be, but is not limited to, a spring, a coil springor a wave spring.

The second side 18 b of the first differential side gear 18 also has aset of teeth 28. The teeth 28 are located radially above the biasingmember 26.

A second end 26 b of the biasing member 26 is in contact with a spinningcomponent or cam ring 30. In one embodiment, the cam ring 30 has aradially inner interior portion 30 a, a radially outer interior portion30 b and a radially outer exterior portion 30 c. The radially outerinterior portion 30 b and the radially outer exterior portion 30 c aregenerally axially aligned with one another. The biasing member 26 is incontact with the radially inner interior portion 30 a of the cam ring30.

The cam ring 30 also has a set of teeth 32 thereon. The teeth 32 arelocated on the radially inner interior portion 30 a. More particularly,the teeth 32 are located radially above a contact point 26 c of thebiasing member 26 on the cam ring 30.

The radially inner interior portion 30 a and the radially outer interiorportion 30 b of the cam ring 30 are both located within the differentialcase 14. The radially outer exterior portion 30 c is located out of thedifferential case 14 and extends through an axial opening 14 c in thedifferential case 14. The radially outer exterior portion 30 c, theradially outer interior portion 30 b and the radially inner interiorportion 30 a may be one piece, unitary and integrally formed, or may beof individual pieces that are connected together.

The radially outer exterior portion 30 c of the cam ring 30 is incontact with an axially movable bushing 34. The bushing 34 is preferablya continuous, ring shaped structure. The bushing 34 may be constructedof a non-magnetic material, such as, but not limited to, plastic. In oneembodiment, the bushing 34 is located radially inboard and axiallyoutboard from the radially outer exterior portion 30 c of cam ring 30.

The bushing 34 is in contact with an-axially movable slide collar 36.The slide collar 36 is constructed of a metallic material that issusceptible to magnetic forces including, but not limited to, steel. Theslide collar 36 is located radially inboard of an electromagnet 38 of anactuator 46.

The electromagnet 38 includes a coil 40 and a coil housing 42. The coilhousing 42 is hollow and encloses the coil 40. In one embodiment, thecoil 40 includes multiple copper wire windings encased in a pottingmaterial within the coil housing 42. The wire windings of the coil 40are connected to a source for electricity (not shown).

The coil housing 42 may be one piece or several pieces connectedtogether. The coil housing 42 and the electromagnet 38 may be located onthe differential case 14. The coil housing 42 may be stationary withrespect to the rotating differential case 14. A bushing 44 may belocated between the coil housing 42 and the differential case 14 tofacilitate relative rotation between the two.

The slide collar 36 is located radially inward from the coil housing 42and is in direct contact therewith. The slide collar 36 can have acomplementary shape to the coil housing 42.

A sensor assembly 50 is located in the differential case 14. Moreparticularly, a sensor assembly 50 may be located in an aperture 14 dthat extends through the differential case 14. In one embodiment, theaperture 14 d is a radially extending aperture 14 d extending through anouter wall of the differential case as shown in FIG. 1.

The sensor assembly 50 can include a printed circuit board (PCB) 52, apower source 54, a transmitter 56 and at least one sensor 58. Thetransmitter 56 can include an antenna and other additional components.In one embodiment, the PCB 52 can include a microcontroller. The PCB 52,power source 54, transmitter 56 and at least one sensor 58 can belocated in a single housing 64, as shown in FIG. 1, or may be located inindividual separate housings in or on the differential case 14.

As shown in FIG. 1, the sensor 58 can be a Hall effect sensor.Additionally, the sensor 58 can be a pressure sensor or a linearposition sensor including, but not limited to, a resistive slide or aminiature-linear variable differential transformer. In one embodiment,the sensor assembly 50 can include a Hall effect sensor and a pressuresensor.

Preferably, the sensor assembly 50 has an interior portion 50 a thatextends radially into the hollow interior 14 a of the differential case14. Preferably, the sensor 58 is positioned within the housing 64 oroutside the housing 64 within the hollow interior of the differentialcase, axially adjacent the cam ring 30. The interior portion 50 a ispreferably located adjacent the radially outer interior portion 30 b ofthe cam ring 30. The interior portion 50 a may be axially locatedbetween the first differential side gear 18 and the cam ring 30 andradially located outboard of the differential pin-ion gear 24.

The sensor assembly 50 is preferably fixed in a non-rotating fashion tothe differential case 14. The differential case 14 is rotatable and whenthe differential case rotates, the sensor assembly 50 rotates with thedifferential case 14. However, the sensor assembly 50 is mounted suchthat there is no relative rotation between the differential case 14 andthe sensor assembly 50. Further, the sensor assembly 50 is fixed axiallyand radially within the differential case 14 for no relative movementwith respect to the differential case 14.

In one embodiment, the sensor assembly 50 includes a pressure sensor 58extending from a side surface 50 b as shown in FIG. 2. The pressuresensor 58 may include a biasing member 66, such as an elastomer orspring.

The pressure sensor 58 is designed to be in contact with the radiallyouter interior portion 30 b of the cam ring 30. The pressure sensor 58may be in constant contact with the cam ring 30, or it may be separatedfrom the cam ring 30 by a closeable gap. In either case, the axialamount the biasing member 66 is moved or compressed by the cam ring 30is sensed by the pressure sensor 58. The biasing member 66 absorbs thelinear translation of the cam ring 30 and generates a proportional-forceon the pressure sensor 58. In one embodiment, the pressure sensor 58 isan SP37 450 kPa pressure sensor or similar. While this is one embodimentof a pressure sensor, other embodiments can include pressure sensors ofother sizes and capacities.

The sensed displacement can be converted to a signal, such as through aPCB 52, transmitter 56 and other electronic components in the sensorassembly 50. The signal can then be wirelessly transmitted by thetransmitter 56 from the sensor assembly 50 to a transceiver 70 and/orcontroller. In one embodiment, the signal may be sent through radiofrequency transmissions or other frequencies.

In one embodiment, the sensor assembly 50 can include a Hall effectsensor 58 located thereon or therein. As shown in FIG. 1, the sensor 58is located in the sensor assembly 50. More particularly, the Hall effectsensor 58 may be located in the radially innermost portion of interiorportion 50 a of the sensor assembly 50. The interior portion 50 a of thesensor assembly 50 may be located radially outward from the differentialpinion gear 24 so that a gap 74 exists between them.

A sensing element 76 is located on or in the radially outer interiorportion 30 b of the cam ring 30. One embodiment of the location, shapeand size of the sensing element 76 is depicted in FIG. 1; however, otherlocations, shapes and/or sizes are possible.

The sensing element 76 can be a magnet. As shown in FIG. 1, the magnet76 can be located on an inner side surface 30 d of the radially outerinterior portion 30 b of the cam ring 30. The magnet 76 is locatedradially outward from the set of teeth 32 on the cam ring 30 andradially outward from the biasing member 26. It is also possible tolocate the magnet 76 on a radially outer surface of the cam ring 30.Further, it is possible to locate the magnet 76 within the cam ring 30,such as within a depression or fully encased within the cam ring 30.

FIG. 1 depicts the magnet 76 in a substantially horizontal orientation.That is, it is horizontal with respect to an axis of rotation A of thedifferential. The magnet 76 may also be oriented in a substantiallyvertical orientation with respect to the axis of rotation A. The magnet76 may also be oriented at an angle, such as at a 45-degree angle, withrespect to the rotational axis A.

The wireless system 10 may also include a receiver/demodulator 80. InFIG. 1, the receiver/demodulator 80 is depicted as located on the coilhousing 42. More particularly, the receiver/demodulator 80 is located ata distance from the cam ring 30 or the differential case 14 so that agap exists between the magnet 76, the sensor assembly 50 and thereceiver/demodulator 80. The receiver/demodulator 80 may also be locatedon the differential housing or elsewhere in the vehicle. Alternatively,the receiver/demodulator 80 can be integrated into other existingvehicle electronics, such as the tire inflation system for the vehicle.

The sensing step, signal creation, any operations by the printed circuitboard 52 and the signal transmission can be powered by the power source54 located in the sensor assembly 50. The power source 54 can be arechargeable power source. In one embodiment, the power source 54 is abattery. More particularly, the power source 54 is a battery that doesnot need to be replaced for the life of the vehicle.

Power consumption from the power source 54 can be controlled bypermitting the sensor assembly 50 to be placed into a sleep mode when itis not needed, such as when the vehicle is turned off or when thespecific system is inactive.

The controller (not depicted) can signal the sensor assembly 50 and/orpower source 54 to “sleep”. In one embodiment, a wireless controller ispart of the receiver/demodulator 80 and/or is in communication withsensor assembly 50 can signal the sensor assembly 50 and/or power source54 to sleep. When the vehicle is turned back on or the wireless system10 is activated, the controller can signal the sensor assembly 50 and/orpower source 54 to turn back on.

The controller and/or transceiver 70 can be located on the differentialhousing or elsewhere in the vehicle. Alternatively, the controllerand/or the transceiver 70 can be integrated into other existing vehicleelectronics, such as the vehicles tire inflation system.

The wireless system 10 permits a signal indicating whether thedifferential is engaged or disengaged to be accurately andinstantaneously determined and signaled to the controller. Thecontroller is communicatively coupled the sensor assembly 50. Thecontroller receives signals generated by the sensors 58 and processesthe received signals to determine the axial displacement of the spinningcomponent. More particularly, the wireless system 10 determines theposition of the cam ring 30 to determine whether it is engaged ordisengaged with the differential side gear 18.

The differential assembly 12 has two modes of operation. In a first modeof operation, the differential assembly 12 is not locked as depicted inFIG. 2. The teeth 32 of the cam ring 30 and the differential side gear18 are not engaged with one another. Instead, there is a gap between theteeth of the cam ring 30 and the differential side gear 18. This modepermits the differential side gears and pinion gears to rotate withrespect to one another.

The second mode of operation begins with electricity being sent to thecoil 40 and the coil wires create a magnetic flux. The current in thecoil 40 causes the coil housing 42 to become magnetized. The sum of thecoil 40 flux and the coil housing 42 magnetism is greater than the sumof the spring force from the biasing member 26 between the cam ring 30and the differential side gear 18 and friction force of the slide collar36, which causes the slide collar 36 to move, as shown in FIG. 3.

Within a few milliseconds of the coil 40 being energized, the magneticflux causes the slide collar 36 to move in the inboard axial direction.The slide collar 36 axially moves the bushing 34, which in turn axiallymoves the cam ring 30 in the inboard axial direction. The cam ring 30axially moves into the differential side gear 18 causing the cam ringteeth 32 to engage with the matching side gear teeth 28.

In an embodiment where the sensor assembly 50 includes a pressure sensor58, as the cam ring 30 moves, it compresses the biasing member 26,increasing pressure on the sensor 58. The sensor 58 processes the newaxial position of the cam ring 30 and communicates to the transceiver70.

In an embodiment where the sensor assembly includes a Hail effect sensor58, the inboard axial movement of the cam ring 30 moves the magnet 76 inthe same direction. When the side gear teeth 28 and the cam ring teeth32 are engaged, such as fully engaged, the magnet 76 is located radiallyadjacent, such as at least radially beneath the sensor 58. A radiallygap exists between the sensor assembly 50 and the magnet 76 so that thetwo are not in physical contact with one another. The sensed magnet 76can be converted to a signal, such as through a printed circuit board 52and/or other electronic components in the sensor assembly 50. The signalcan then be wirelessly transmitted from the sensor assembly 50 to thereceiver/demodulator 80. The signal may be sent such as through radiofrequency transmissions, or other frequencies, or through inductivecoupling.

The sensing step, signal creation, any operations by the printed circuitboard 52 and the signal transmission can be powered by the power source54 located in the sensor assembly 50.

The above-described wireless system 10 permits a signal indicatingwhether the differential assembly 12 is engaged or disengaged to beaccurately and instantaneously determined and signaled to thecontroller. More particularly, the wireless system 12 determines theaxial displacement of the cam ring 30 to determine whether it engages ordisengages with the differential side gear 18.

When it is no longer desired for the differential assembly 12 to be inthe engaged position, the electricity is removed from the coil 40. Thebiasing member 26 biases the cam ring 30 away from the differential sidegear 18, thus, separating the two.

In one embodiment, as shown in FIG. 4, the power source 54 can includean energy generation system 110 for the sensory assembly 50 withabove-described system. The energy generation system 110 may be alwaysemployed, selectively used, or used entirely on its own without theabove-described wireless system 10. For example, the wireless system 10can include the power source 54 that may be used when the vehicle is notmoving or the differential is not rotation, but the energy generationsystem 110 may be used at all other times. The energy generation system110 may be connected to the power source 54 in the sensor assembly 50, abattery outside of the sensor assembly 50 and/or a capacitor-located inor adjacent the sensor assembly 50.

In one embodiment, as depicted in FIG. 4, the energy generation system110 includes a coil 112, such as a metal coil of wires, located in or onthe differential case 14. The coil 112 can be fixed with respect to thedifferential case 14 and rotates with it. The coil 112 is electronicallyconnected to the power source 54 of the sensor assembly 50. Preferably,the coil 112 is located adjacent, on or in the sensor assembly 50 sothat an energy efficient, relatively short and inexpensive electricalconnection can be made.

The energy generation system 110 also includes a magnet 114 located inor on a stationary housing 116. The stationary housing 116 is radiallyoutward from the differential case 114. The coil 112 and the magnet 114are preferably located proximate on another. In one embodiment, the coil112 and magnet 114 are located radially and axially aligned with oneanother, but may also be offset from one another in either the radial oraxial direction.

As the differential case 14 selectively rotates within the housing 116,the coil 112 rotates by the magnet 114. Rotation of the coil 112 by themagnet 114 generates an electric current in the coil 112. The currentcan be provided to the power source 54 to assist in the maintaining thepower source 54 or effectively replacing the power source 54 if needed.

FIG. 4 depicts the energy generation system 110 including one coil 112and magnet 114; however, the energy generation system 110 can include aplurality of coils and/or magnets. The additional coils/magnets can beused depending on the electrical power generating needs of the overallwireless system 10. By the way of example only, one embodiment mayinclude single magnet 114 located as described above, and then aplurality of spaced apart coils located as described above. The coil 112or coils can generate electricity when magnetic flux goes through andaround the coil 112.

In another embodiment, the energy generation system 110 can include asmall weight and magnet that rotate about a spider shaft 16 or otherstructure. The weight and magnet are connected to each other, preferablydirectly attached to one another. The weight is connected to thedifferential case 14 and selective rotation of the differential case 14imparts rotation to the weight. The inertia of the moving weight causesthe magnet to pass adjacent to, or directly over or about, the coil 112.The magnet thus generates an electric current in the coil 112. Thecurrent can be provided to the power source or battery 54 to assist inmaintaining the battery 54 or effectively replacing the battery 54 ifneeded. It can be appreciated that more than one weight/magnet systemmay be used to generate the electrical power needed for the system.

In one embodiment, as shown in FIGS. 5 and 6, the differential case 14may include flux path features 210 formed integrally in the differentialcase 14 to provide a flux path. The flux path features 210 can beintegrally formed, one piece and unitary with the differential case 14,and/or can be separately attached. The flux path features 210 can beconstructed out of an electrically conductive material including, butnot limited to, steel.

While FIGS. 5 and 6 show one embodiment of the flux path features 210,the flux path features 210 may be of various shapes and sizes and thelocation of the flux path features 210 in relation to the differentialcase 14 can vary. FIGS. 5 and 6 depict a portion of the differentialcase 14 with the flux path features 210 located adjacent theelectromagnet 38. In this embodiment, the sensor assembly 50 is locatedin an axial opening 14 e in the differential case 14 from the cam ring30 as shown in FIG. 5. The flux path features 210 of the differentialcase 14 are located between the electromagnet 38 and the sensor assembly50.

The flux path features 210 may include a curvilinear groove 210 a inwhich a coil 212 is placed. The groove 210 is shown as circular or ovalwith a constant depth and width, but other shapes and dimensions arepermissible. The coil 212 can be placed in the groove 210 a so that theupper surface of the coil 212 is flush with the outer surface of thedifferential case 14 as shown in FIG. 6. The flux path is depicted byarrows in the differential case 14 in FIG. 6.

In another embodiment, the energy generation system can use inertiagenerated within the system to move a mass and create electricity. Inthis embodiment, the energy generation system 310 is a shaker-typeenergy generation system as depicted in FIGS. 7a-b . The shaker-typeenergy system 310 includes a magnet 312 that selectively moves, such asaxially, within a coil 314 of wire that at least partially surrounds themagnet 312. The coil 314 is connected to the power source 54 to assistin maintaining the power source 54 or effectively replacing the powersource 54 if needed. A biasing member 318 including, but not limited to,a spring, can be used to selectively located the magnet 312 in a homeposition.

The biasing member 318 is located within a housing 320 that houses themagnet 312 as shown in FIG. 7b . The biasing member 318 may be locatedon one side of the magnet 312, but other locations and arrangements arepermissible. The magnet 318 is permitted to slide in a larger diametersection 320 a of the housing 320 compared with the section of thehousing the houses the biasing member 318 as shown in FIG. 7 b.

The energy generation system 310 is connected to the differential case14 so that for a predetermined amount of acceleration and/or declarationof the differential case 14, the magnet 312 compresses the biasingmember 318 and an electric current is generated by virtue of themovement of the magnet 312 in the coil 314.

The energy generation system 310 may be located on the differential case14, partially within the outer wall of the differential case 14,completely within the outer wall of the differential case 14 or withinthe differential case 14.

It can be appreciated that any number of the shaker-type energy systems310 can be used based on the electrical power needs of the wirelesssystem 10.

In accordance with the provisions of the patent statutes, the presentinvention has been described in what is considered to represent itspreferred embodiments. However, it should be noted that the embodimentscan be practiced otherwise than as specifically illustrated anddescribed without departing from its spirit or scope.

We claim:
 1. A wireless system for determining the displacement ofspinning components of a differential assembly, comprising: adifferential case having a hollow interior space; the differentialassembly including an actuator including an electromagnet having a coiland a spinning component selectively engaged with a differential geararrangement; and at least one sensor assembly non-rotatably mounted tothe differential case including at least one sensor communicativelycoupled to a printed circuit board, a transmitter and a power source,wherein the differential case houses the differential gear arrangement,wherein a portion of the sensor assembly extends axially and radiallywithin the differential case and the at least one sensor is positionedaxially adjacent to the spinning component of the differential assemblyin the hollow interior space of the differential case, wherein the atleast one sensor directly senses the axial displacement of the spinningcomponent, wherein the sensor assembly generates a signal representingthe axial displacement of the spinning component, and wherein thetransmitter is wirelessly coupled to a receiver positioned outside thedifferential case.
 2. The wireless sensing system of claim 1, whereinthe power source is rechargeable power source.
 3. The wireless system ofclaim 1, wherein the power source is a battery.
 4. The wireless systemof claim 1, wherein the power source further comprises an energygeneration system.
 5. The wireless system of claim 4, wherein the energygeneration system is a shaker-type system.
 6. The wireless system ofclaim 5, wherein the energy generation system is positioned on thedifferential case.
 7. The wireless system of claim 4, wherein the energysystem includes at least one coil connected to the power source andmounted on the differential case adjacent the sensor assembly and atleast one magnet connected to a stationary housing positioned radiallyoutward from the differential case.
 8. The wireless system of claim 7,wherein the differential case includes at least one flux path featureformed integrally therein.
 9. The wireless system of claim 8, whereinthe flux path feature includes a groove formed integrally in thedifferential case, wherein the groove includes a coil having an uppersurface that is even with an outer surface of the differential case. 10.The wireless system of claim 1, wherein the at least one sensor is aHall effect sensor having a sensor element attached to the spinningcomponent radially inward from the sensor.
 11. The wireless system ofclaim 1, wherein the at least one sensor is a pressure sensor extendingaxially away from the sensor assembly toward the spinning-component. 12.The wireless system of claim 1, further comprising a controller incommunication with the sensor assembly.
 13. The wireless system of claim1, further comprising a biasing member having a first end and a secondend, wherein the first end is connected to the differential geararrangement and the second end is connected to the spinning component.14. The wireless system of claim 11, wherein the biasing member is aspring.
 15. The wireless system of claim 1, wherein the transmitter usesradio frequency transmissions.